Over 45% of American women 20-39 years old are at risk for type 2 diabetes, cardiovascular disease, and other health conditions because they are overweight or obese. The prevalence of overweight/obesity is disproportionately high among low-income women. Unfortunately, advances in prevention of obesity have generally failed to translate evidence-based knowledge to real-world settings. To have a broad public health impact on obesity, it is critical to design interventions that have the potential for implementation, adoption, dissemination, and long-term maintenance in major community-based programs such as the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) and Extension. Working with 4 WIC and 6 Michigan State University Extension (MSUE) programs, the research team proposes to conduct a randomized controlled trial (RCT) to test the effectiveness of the Mothers In Motion intervention (MIM). The MIM aims to prevent weight gain among African American (AA) and white overweight/obese WIC mothers18- 39 years old by promoting healthy eating, physical activity, and stress management. The MIM will deliver theory-based, culturally-sensitive intervention messages via a combination of DVDs featuring AA and white overweight/obese WIC mothers who will participate in a healthy lifestyle intervention patterned after MIM and peer support group teleconferences (PSGTs) led by MSUE nutrition (paraprofessional) educators who will be trained in motivational interviewing. Participants (N = 465) will be randomly assigned to an intervention or control group. The intervention group will receive usual WIC care and DVDs (watched at home) and call in PSGT discussions. The control group will receive usual WIC care. The primary outcome will be the difference in changes of body weight at the final follow up. Secondary outcomes will include improvement of fasting plasma glucose, triglyceride, and cholesterol. Mediating factors will include improvements in dietary fat, fruit, and vegetable intake; physical activity; stress; feelings; and personal (self-efficacy and emotional coping response) and environmental (social support) factors from the Social Cognitive Theory. The RE-AIM model will guide process evaluation of the MIM. The specific aims are to 1) develop and refine the MIM DVDs and a booster DVD training program for PSGT nutrition moderators, 2) evaluate the effectiveness of the MIM via a RCT, comparing the MIM to usual WIC care in preventing weight gain among AA and white overweight/obese WIC mothers 18-39 years old, 3) evaluate key factors related to implementation of the MIM including reach, adoption, implementation, cost effectiveness, and maintenance over time, and 4) initiate plans to facilitate and support national dissemination once the study is complete. If MIM shows effectiveness, it will have a favorable impact on public health/community programs: The DVDs and PSGTs will be disseminated in WIC, Extension, clinical practice (e.g., OB/GYN offices), and other settings (e.g., Community Health Centers) that promote healthy lifestyles for similar target audiences. We also anticipate a concomitant benefit on childhood obesity.